In order to investigate the effects of the specific heat, thermal conductivity and heat of pyrolysis reaction on the temperature distribution and temperature variation of a single printed circuit board (PCB) particle during the pyrolysis process, a mathematical model is established and the heat transfer process is simulated. The results show that the effects of the specific heat on the temperature distribution and temperature variation are different for different parts of the PCB particle. The effect on the center part is very obvious. The biggest temperature deviation is 12% when considering and ignoring the variation of specific heat with temperature. The anisotropy of the thermal conductivity has a certain impact on the variation of the temperature. The PCB particle begins to decompose at about 300 °C. The pyrolysis reaction needs to absorb much heat to break the chemical bonds, which will delay the temperature rise. In addition, the thermogravimetric (TG) experiment is carried out to verify the rationality of the model. By comparing the TG and differential thermogravimetric (DTG) curves between the experiment and the simulation, there is a 9.08% difference at the final pyrolysis temperature between the two mass losses, which means the mathematical model is reasonable.